JPS6111492Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel supply control device for an internal combustion engine.

Some internal combustion engines for automobiles perform speed control, engine rotation speed control, run-on prevention, etc. by controlling fuel supply to the engine. At this time, an electromagnetic fuel supply control valve is often used as a fuel supply control device, but the conventionally used electromagnetic fuel supply control valve has a valve member 3 connected to a main jet 5 as shown in FIG. The fuel is cut off by coming into contact with the provided seat portion 4. However, when using a control valve with such a structure, it is very difficult to align the axes of the valve member 3 and the seat portion 4, and if the axes are misaligned, complete fuel cut may not be performed and the initial purpose may not be achieved. There was a problem in which I was not able to achieve the desired goal.

Therefore, a fuel supply control valve in which a seat member 7 and a valve member 3 are integrated as shown in FIG. 2 is provided in the slow system passage 14 of the carburetor to prevent run-on. However, in this case, it can only be used to prevent run-on.
It would be impossible to control everything such as speed control and engine speed using a single fuel supply control valve.

This invention uses a single electromagnetic fuel supply control valve to ensure reliable control of fuel supply when necessary, such as run-on prevention, speed control, engine speed control, etc. At the same time, the following problems that arise when adopting such a configuration are also taken into consideration.

That is, in order to achieve the above object, the valve must be provided at the fuel outlet 15 of the float chamber 16 to control the supply of fuel. By the way, when configured in this way, the volume of the float chamber 16 cannot be increased too much from the viewpoint of preventing the generation of evaporative gas, and since the float 22 is contained, the entire electromagnetic fuel supply control valve 2 is not allowed to float. It is difficult to enter the chamber 16. Furthermore, it is not desirable to insert the electromagnetic fuel supply control valve into the float chamber 16 because of the heat generated from the coil portion 2'. Therefore, only the cylindrical member 6 must be inserted into the float chamber 16 by penetrating its bottom.

However, since the carburetor 17 is attached to the upper part of the intake manifold 23, it becomes quite hot due to heat transfer from the engine, and the atmospheric temperature in the engine room is also quite high, and bubbles are frequently generated from the wall surface of the float chamber 16. ing. In the summer, the outside temperature is high, so the gasoline temperature in the float chamber 16 rises to 70°C to 80°C, and this tendency is particularly remarkable. Furthermore, there are many bubbles generated from the slow system path where the fuel flow rate is low.
Bubbles remain in the fuel passage 19 as well.

Therefore, when the valve member 3 separates from the seat member 7, air bubbles enter the cylindrical member 6 through the fuel inlet 12.
Also, when the valve member 3 is seated on the seat member 7, the air bubbles remaining in the fuel passage 19 pass from the fuel outlet 9 through the constriction part 8,
If air bubbles remain in the fuel reservoir 21 formed between the throttle part 8 and the seating part of the valve member 3, a phenomenon such as swelling will occur.

By the way, if the volume of this fuel reservoir 21 becomes large or the opening position of the fuel inlet 12 is not appropriate, the amount of air bubbles retained inside will increase, resulting in poor response during acceleration and damage to the carburetor fuel system when hot. When the temperature rises, the escape of bubbles generated in the fuel passage 19 becomes difficult, and when the valve member 3 separates from the seat member 7, especially at low speeds or idling, the fuel runs out instantaneously, making the engine rotation unstable. When this happens, something happens. The present invention solves this problem by appropriately selecting the opening position of the fuel inlet 12.

The present invention will be explained below with reference to the drawings. Fig. 3 is a drawing showing an embodiment of the present invention, in which 1 is an operation control device for an electromagnetic fuel supply control valve 2, which controls vehicle speed, engine speed,
By detecting the position of the ignition switch, a command for ON/OFF operation of the electromagnetic fuel supply control valve 2 is given to control the fuel supply timing.

The electromagnetic fuel supply control valve 2 consists of an electromagnetic coil portion 2' exposed outside the carburetor, and a cylindrical member 6 inserted into the float chamber through the bottom thereof, and a valve member 3 is housed inside. A seat member 7 is press-fitted into a portion of the valve member 3 that has a diameter smaller than the inner diameter of the cylindrical member 6 on which it slides. is controlled. In addition, this aperture part 8
may be provided on the casting body side of the carburetor 17.

Further, the cylindrical member 6 is provided with protrusions 10, 10 on the side of the fuel outlet 9, and a groove portion 11 is formed therebetween, into which an O-ring 20 is inserted. Furthermore, a fuel inlet 12 is provided in the cylindrical portion of the cylindrical member 6 to introduce the fuel in the float chamber 16 into the cylindrical member 6.

The protrusion 10 of the electromagnetic fuel supply control valve 2 having the above configuration is inserted into the fuel outlet portion 24 of the float chamber 16, and the O-ring 20 prevents fuel from flowing from this portion to the fuel outlet 15. It's summery.
The other end is fastened to the carburetor 17 via a seal member 25 and a gasket 26.

Here, regarding the opening position of the fuel inlet 12 of the present invention, as shown in FIG. When the length of the inserted pipe is Y, it is appropriate that the fuel inlet 12 is X1/2Y. Further, it is desirable that the positional relationship between the fuel inlet 12 and the seat portion 7' of the seat member 7 is as close as possible. Furthermore, the fuel reservoir 21
If the volume of the engine is Vcc, it is best to keep V to 0.1% or less of the engine displacement.

Figures 6 and 7 show experimental results when an electromagnetic fuel supply control valve to which the present invention is applied and a fuel supply control valve to which the invention is not applied were used in a 4-cycle 550 c.c. engine.

The dimensions of the electromagnetic fuel supply control valve used are as follows:
In the case of Figure 6, X = 13mm, Y = 30mm, V = 0.057cc
In the case of Figure 7, X = 0.01% of the engine displacement.
It was 25mm, Y = 30mm, V = 0.127cc, which was 0.023% of the engine displacement.

The figure shows the relationship between rotational speed fluctuations and time when the electromagnetic fuel supply control valve 2 cuts off fuel due to the operation of the operation control device 1 and then starts supplying fuel.

As is clear from the figure, with the electromagnetic fuel supply control valve of the present invention, the fluctuation range of the rotation speed can be suppressed to about ±30 rpm of the required rotation speed, which is different from the rotation speed fluctuation of a normal engine without a control valve. Almost the same. On the other hand, in the case of an electromagnetic fuel supply control valve in which the opening position of the fuel inlet 12 is not appropriate, that is, X>1/2Y, the rotation speed fluctuation range is ±70 rpm, as shown in Fig. 7. Rotation continues to be unstable.

This condition continues because many air bubbles remain in the fuel reservoir 21, so even if the valve member 3 is separated from the seat member 7, fuel cannot be smoothly and continuously supplied. This is because if a large amount of fuel is supplied all at once, causing a fuel shortage and the rotational speed drops, or if a large amount of fuel is discharged all at once and the rotational speed increases, the following phenomena occur. Furthermore, this condition continues until the engine is stopped, the temperature of the engine decreases, and bubble generation stops. If this condition continues, it will become unusable as an engine.

In this way, even if electromagnetic fuel supply control valves of the same shape are used, the above-mentioned difference occurs depending on the opening position of the fuel inlet 12, when the fuel inlet is located on the left in Fig. 3. Since the area of the float wall in contact with gasoline is large, and the control valve mounting area is at high temperature due to heat generation from the electromagnetic coil, a large amount of air bubbles are generated. moreover,
The further the inflow port is to the left, the larger the space where bubbles stay, the larger the amount of bubbles that stay, and the longer the narrow path becomes, making it harder for bubbles to escape into the float chamber.

On the other hand, when the fuel inlet opening is provided at the X1/2Y position, the conditions for bubble generation from the float chamber wall surface do not change much, but the influence of heat generation from the electromagnetic coil 2' is reduced. Furthermore, since the space in which the bubbles stay is small and the narrow path is shortened, the bubbles can easily escape, and there is no problem in terms of responsiveness.

In addition, when the opening position of the fuel inlet 12 is provided at X1/2Y in this way, the valve member 3 inevitably becomes long, but in this case, the cross-sectional shapes of the valve member 3 and the cylindrical member 6 are made similar. In this case, since the cylindrical member 6 serves as a sliding guide member for the valve member 3, there is a problem in the machining accuracy of both parts, and since it is attached to a vibrating body such as an engine, abnormal wear occurs locally due to vibration. Due to this, the sliding resistance between the two increases and malfunction occurs. Therefore, when adopting such a structure, for example, if the cylindrical member 6 has a cylindrical cross-sectional shape as shown in FIG. What is necessary is to provide a radius in the dimensions and guide this portion with the cylindrical member 6. By doing so, the space formed between the cylindrical member 6 and the valve member 3 is filled with fuel to provide a damper effect against vibrations of the valve member 3, thereby maintaining smooth operation. The cross-sectional shapes of the valve member 3 and the cylindrical member 6 are not limited to those described above, and of course any combination may be used as long as it produces the above effects.

As described above, according to the present invention, by using a single electromagnetic fuel supply control valve, it is possible to control the fuel supply for speed control, engine speed control, and run-on prevention pipe. It is also possible to prevent deterioration of drivability due to instability of the engine speed due to the generation of air bubbles, which is a problem.

[Brief explanation of the drawing]

Figure 1 is a sectional view of the main parts of a carburetor with a conventional electromagnetic fuel supply control valve, Figure 2 is a partially enlarged view of a conventional electromagnetic fuel supply control valve, and Figure 3 is an electromagnetic fuel supply according to the present invention. Fig. 4 is an enlarged view of the main part of the electromagnetic fuel supply control valve of the present invention, Fig. 5 is a sectional view taken along line A-A in Fig. 3, and Fig. 6 is a cross-sectional view of the main part of a carburetor having a control valve. FIG. 7 is a diagram showing engine speed fluctuation characteristics of an electromagnetic fuel supply control valve not according to the present invention. 2... Fuel supply control valve, 2'... Electromagnetic coil section, 3... Valve member, 7... Seat member, 7'...
Seat part, 8... Throttle part, 12... Fuel inlet, 21
...Fuel reservoir.

Claims (1)

[Scope of utility model registration request] It consists of an electromagnetic coil part provided outside the float chamber of the internal combustion engine, and a cylindrical member provided inside the float chamber. A valve member and a seat member on which the valve member is seated are provided inside the valve member, and a fuel inlet port communicating between the inside and outside of the cylindrical member is opened so that the opening position is 1/2 of the insertion length of the cylindrical member into the float chamber. An electromagnetic fuel supply control valve for an internal combustion engine, characterized in that it is provided on the outlet side.